I'm able to enter Uboot and use commands. Everything seems to work, but the boot process of the plug intrrupts. I'm also not able to reflash anything with the Sheeva-Installer. I tried to recover my Plug with it. I get tons of permission error when trying to flash, although I'm root.

The USB Stick is recognized in uboot, but i can't install debian on it, if i try to install everything via tftp.